Biological studies incorporating stable C, N, S and O isotopes

- In my research stable isotopes (C, N, S and O) have become indispensable in answering questions related to nutritional pathways in terrestrial mammals, benthic-pelagic coupling in lakes, biomagnification of contaminants in aquatic ecosystems, niche partitioning and the determination of resource use overlap, study of trophic polymorphisms, the measurement of thermal habitat use and prediction of climate change impacts on northern fish populations and the study of other large scale ecosystem processes. In recent years (2003-05) the proportion of publications using isotope methods has risen to 58% from 19% in previous years (2000-02), such that in the last six years isotope methods figure directly in 38% of all publications.

The trend is expected to continue as my students (n=8) now all use isotope mass spectrometry in thesis-related study, be it as a primary or supplemental analytical tool.

The UW-EIL features an array of specialized and technically advanced equipment that is of vital interest to this research, both because it provides novel instrumentation not widely available elsewhere and, importantly, because it has the capability to conduct high volume throughput analysis. As ecological use of stable isotopes has increased, it has become increasing important to increase the number of samples analysed.

Novel description of a relationship no longer suffices. Accurate description of sample and case variability is critically needed and can only be obtained from accurate, high volume analysis. The Uw-EIL has perfected the delivery of such analyses with an integrated team of specialists.

Advances in oxygen isotope measurement have facilitated the application of stable isotope analysis to archival fish otoliths for use in climate effect studies. For our research, it was the recognized capability of the UW-EIL that was crucial to being able to undertake climate-impact research and be awarded research grants to study climate change impacts on northern fishes. This analysis will require precise, high volume analysis that no other lab in Canada can currently provide. Herein lies the uniqueness of the Waterloo facility – its ability to provide apparently routine values on large numbers of samples in a timely manner. Only with such capability can broad scale macro-ecological phenomenon (e.g. climate change impacts) be clearly understood.

Similarly, a second case in point is the S-isotope capability that has allowed my students to undertake research collaborations with Fisheries and Oceans Canada to assess nearshore habitat use by keystone northern fish species in the Beaufort Sea. Without the continued development, measurement and analytical expertise in the UW-EIL, advanced training of graduate students in this laboratory would have to be significantly curtailed. Without the high quality services of the UW-EIL, this laboratory would not achieve the research success it does, including the Dempson & Power study reviewed in Nature (429:982).